1. Field of the Invention
The present invention relates to mountings for filter cartridges and, more particularly, to seals for sealing opposed ends of a filter element of a filter cartridge that accommodate for axial movement of the filter cartridge without compromising the seals.
2. Description of Related Art
Filter cartridges have been in use for decades to filter with a cylindrical filter element a fluid flowing radially therethrough. Usually, the fluid flow through the filter element is from its external surface to its internal surface. Thereafter, the fluid is exhausted axially from one end. Each opposed end of the filter element include a compressible annular cap mating with an annular knife edge of a housing. Each annular knife edge forms a seal with the respective end cap as a function of the compression therebetween imposed by the housing and the elasticity and resiliency of the filter element. Over a period of time, the end caps tend to acquire a set and the pressure against the corresponding annular knife edge diminishes to the point where the seal is compromised.
The resiliency and elasticity of the filter element providing a bias against the opposed annular knife edges diminish over a period of time or through deterioration caused at least in part by interaction with the fluid being filtered. The loss of resiliency and elasticity compromises the bias force against the opposed annular knife edges. The pressure differential on opposed sides of each annular knife edge increases as the filter element becomes more and more clogged. Such increase in pressure differential, coupled with the compromised sealing bias, will cause leakage. The resulting leakage will contaminate the previously filtered fluid with potentially disastrous results.
The previously known solution to extend the filtering life of a filter cartridge has been that of increasing the pressure bias of the annular knife edges on the opposed ends of the filter element. At best, this solution increases the life of the sealing function of the annular knife edges for a limited period of time.
Another problem with conventional filter cartridges is that tolerances of filter cartridges from different manufacturers are not the same. Thus, a presumably standard sized filter cartridge may not fit a housing for such filter cartridge sufficiently well to maintain a seal for a reasonable period of time before being affected by the above described modes of deterioration.
A housing for a filter cartridge includes a cylinder having a closed bottom for receiving the filter cartridge and a top threadedly engageable with the open end of the cylinder to close the housing. An inlet proximate to the bottom of the cylinder introduces fluid to be filtered to the exterior surface of the filter cartridge and an outlet in axial alignment with the filter cartridge extends through the top for discharge of the filtered fluid. An end cap on the filter cartridge includes a circular sleeve for receiving a stud extending inwardly from the bottom of the cylinder and an O-ring disposed therebetween serves as a seal to prevent inflow of unfiltered fluid into the axial center of the filter cartridge. A similar end cap is disposed at the other end of the filter cartridge, its circular sleeve circumscribes a hollow stud defining the outlet and an O-ring disposed between the stud and the circular sleeve prevents mixing of the filtered and unfiltered fluids. The use of the O-rings between the respective circular sleeves and studs accommodates axial translation of the filter cartridge without compromising the respective seals. By having the surface area radially external of the circular sleeve of one of the end caps greater than that of the other end cap provides a pressure bias induced by the inflowing unfiltered fluid to urge the filter cartridge in the direction of the end cap with the lesser area subject to the inflowing unfiltered fluid. Upon axially stacking two or more filter cartridges, an O-ring is placed intermediate overlapping circular sleeves of adjacent cartridges to maintain the seal at the junction of the filter cartridges to preclude mixing of the filtered and unfiltered fluids.
It is therefore a primary object of the present invention to provide seals at opposed ends of a filter cartridge that do not depend upon resiliency and elasticity of the filter element.
Another object of the present invention is to provide seals for a filter cartridge that accommodate axially translation of the filter cartridge without compromising the respective seals.
Yet another object of the present invention is to provide sealing elements at opposed ends of a filter cartridge to permit use of a single or axially stacked filter cartridges within a housing without compromising the seals necessary to prevent mixing of filtered and unfiltered fluids flowing through the housing.
A further object of the present invention is to provide a housing for a filter cartridge which does not compress the filter cartridge to establish seals to control flow of the fluid to be filtered therein.
A yet further object of the present invention is to provide an end cap for a filter cartridge which positionally maintains an ultra-violet lamp assembly in fixed position therewithin.
A still further object of the present invention is to provide an axially translatable filter cartridge disposed in sealed relationship within a housing for supporting an ultra-violet lamp assembly therewithin.
A still further object of the present invention is to bias a filter cartridge toward one end of an enclosing housing as a function of the pressure of the inflowing fluid to be filtered.
A still further object of the present invention is to provide an inexpensive filter cartridge and housing having seals not affected by deterioration of the resiliency and elasticity of the filter element.
A still further object of the present invention is to provide a method for sealing a filter cartridge within a housing.
The and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds.